This invention relates to the field of the manufacture of motors and other electrical devices requiring densely-packed windings.
An electric motor works by the magnetic attraction or repulsion between a moving part (the rotor) and a fixed part (the stator). The required magnetic attraction or repulsion is produced by electromagnets formed by winding wire around a core through slots. To maximize the magnetic field available, and therefore the force of attraction or repulsion exerted by the electromagnet, one must maximize the number of turns of wire, or the conductor cross-section, so as to maximize the current that can be put through the wire. But for a given available space, the number of turns of wire, and the size of the wire, that can be wound around the core is limited.
Maximizing the conductor cross-section means minimizing the cross-sectional area occupied by the insulation on the wire, and minimizing the unused space between wires. In the ideal case, the windings are so densely packed that the space between wires, and the space taken by the insulation, are negligible. In this ideal case, the efficiency of the motor is maximized because, for a given motor size, the diameter of the conductors forming the windings can be increased, thereby substantially reducing resistive losses, which are proportional to the square of the current. But in practice, it is difficult even to approach the goal of the ideal case. For a given cross-sectional area available for winding a coil, one can generally fill only 40%, economically, of the cross-sec tional area with actual conductors. The insulation on the wire, and around the slot, and the small but finite voids between usually round wires, occupy the balance of the cross-section.
The present invention provides a method of making a monolith comprising a plurality of windings, wherein the windings are packed with high density. The windings formed according to the present invention occupy a substantially greater percentage of the cross-sectional area than do windings formed in the conventional manner. Thus, the present invention greatly increases the efficiency of an electric motor. With the present invention, for example, one can, without increasing the size of the motor, increase the diameter of the conductors forming the windings, or one can reduce the total cross-sectional area of the conductors and use the saved space to provide more iron in the structure, thereby increasing its magnetic saturation. Further, the inherent temperature limitation of wire insulating material, which must withstand the flexing of the winding operation, is overcome by manufacturing refractory material in place, as a solid monolith, thereby greatly increasing the capacity of the product to withstand high temperatures.